1. Field of the Invention
The present invention relates to a playback apparatus and a continuous-playback method for playing back signals from recording media; the playback apparatus and the continuous playback method allow a recording medium to be replaced with another one. In particular, the present invention relates to a playback apparatus and a continuous-playback method employing a facility for replacing a disk recording medium with another one, wherein memory is used for temporarily storing a signal read from the disk recording medium.
2. Background of the Invention
A disk playback apparatus having a disk replacing function has been widely disclosed in documents such as U.S. Pat. Nos. 4,614,474, 4,734,814, 4,701,900 and 4,755,978. In the case of a disk playback apparatus with a disk replacing function, there is much less chance of an optical disk recording medium being touched by hands during replacement. Accordingly, such a disk playback apparatus can well prevent the user from injuring the optical disk or leaving his fingerprints on the optical disk during replacement.
In the disk playback apparatus equipped with such a disk replacing facility, an optical disk is selected by pressing a key among a plurality of optical disks. The selected optical disk is then mounted on a disk playback unit wherein a playback operation is carried out. The disk playback apparatus is so designed that a plurality of optical disks are accommodated in a disk magazine which is mounted on a disk unit. The disk playback apparatus drives a disk replacing mechanism in order to fetch a desired optical disk or a so-called compact disk from the disk magazine. The compact disk fetched from the disk magazine by the disk replacing mechanism is then mounted on the disk playback unit. As the playback operation on the optical disk mounted on the disk playback unit is completed, the disk replacing mechanism removes the optical disk from the disk playback unit and returns it to its original place in the disk magazine. Another optical disk selected by pressing the key or a next optical disk to undergo a playback operation in accordance with information on a playback order programmed in advance is fetched again from the disk magazine and mounted on the disk playback unit. In this way, the playback operation is carried out repeatedly.
In the case of a disk playback apparatus with such a disk replacing function, however, the user cannot identify what optical disks are accommodated in a disk magazine and, thus, what information is stored in the optical disks once the disk magazine has been mounted on the disk playback apparatus unless the user removes the disk magazine out of the disk playback apparatus.
In order to solve the problem described above, a disk playback apparatus, that allows only part of information stored in each optical disk mounted therein to be played back, has been proposed. To be more specific, in the case of a compact disk containing a plurality of songs, only the head portion of each song is played back for a fixed time. For details, refer to a document such as GB-B-2107106 for example.
Even when a disk playback apparatus is equipped with a disk replacing facility as described above, the output signal by the disk playback unit is cut off while a disk is being replaced with another one, inevitably resulting in a mute period of time. In addition, the generation of such a soundless gap cannot be avoided even if the disk playback apparatus having a disk replacing facility is equipped with an additional function for playing back pieces of information stored in an optical disk only for a fixed period of time.
Moreover, in the case of a disk playback apparatus with such a disk replacing function, an optical disk is replaced with another one only after a playback operation carried out by the disk playback unit on the optical disk has been completed. As described above, a next optical disk is fetched from the disk magazine and then mounted on disk playback unit replacing the one that has just completed the playback operation in the disk playback unit. The user has to wait for a long time before the playback operation on the next optical disk can be started.